Brown skin and sunscreen

If you live outside South Asia, you cannot help being bombarded with
news and advice about sunscreen. Exposure to the sun, we
hear, causes skin cancer, assorted other skin problems, and
wrinkles. In South Asia, however, the topic rarely emerges. To most of
us with our varying shades of brown skin, it is not obvious whether
our risk is as high as Caucasians, if we've just been ignorant all
these years, and if we do need sunscreen, what SPF we should use. This
page is an attempt to collect the scientific facts about sun exposure
that are relevant to people from the subcontinent.

UV radiation

It's the UV wavelength in solar radiation that is
responsible for skin damage. UV constitutes about 5% of the total
solar radiation, but is responsible for all the skin damage.
UV comes in two flavours, A & B. A (320-400 nm) has
lower energy , so that it penetrates more deeply but does
not burn skin as easily. 98% of UV radiation is UV-A. UV-B (290 - 320 nm) has higher
energy, penetrates only the outer skin layers, but causes skin to
burn easily. It was formerly thought that only UV-B contributed
to skin damage, but evidence is mounting (see Ref 2 for example) that
both forms of UV can damage the skin.

UV-A is more or less constant throughout the year, and is not absorbed
by the ozone layer. UV-B increases in
summer, at higher altitudes and closer to the equator. (so you are at
most risk when climbing Mt. Kilimanjaro in December!) It is partially
absorbed by the ozone layer, and thus is highest in places like South
Africa and Australia where the ozone layer is thin.

Melanin

Melanin is the pigment that makes skin brown. People with more melanin
have darker skin. Melanin absorbs UV and is thus a natural
sunscreen, and is probably the reason that dark skinned people have
a tenth of the skin cancer rate of fairer folks. When fairskinned
people are exposed to the sun,
this stimulates melanin production in their skin, thus giving them a
'tan', but along the way causes lots of skin damage.
The two most common forms of skin cancer, basal cell carcinoma and
squamous cell carcinoma, are found largely in fairskinned people.
(Ref
4.)

Some Indians, Pakistanis and Afghans have very light skin and
eyes, which may indicate that their risk factors are similar to those
of Southern Europeans (Italians, Spanish, Greeks). This is a lower
risk level than that of Europeans with Celtic ancestry.

Apart from cancer, sun exposure will also eventually cause everyone to
wrinkle, though this effect is also less for those with darker skin.
This wrinkling is called "premature aging", and skin becomes thick,
wrinkled and leathery. In many countries this is considered the normal
result of aging, but it can be prevented to some extent by reducing
sun exposure.

Research

There is very little research on sun protection for dark-skinned people.
A search of PubMed shows that there is lots of research on
skin damage, but the abstracts indicate that almost all the research
has been performed on fair-skinned subjects. Several studies have
noticed racial differences in skin cancer rates, but there are few
studies within South Asian populations. Most web pages that list
risk factors and SPFs are based on Caucasian skin.

Risk factors:
People with skin types I, II and III are at greatest risk.

I = pale white

II = white

III = white (average)

IV = beige or lightly tanned

V = moderate brown or tanned

VI = dark brown or black

(from Ref 8)

The Phillips skin type
table (PDF) has a self-test of skin type. Chances are you will be
able to identify your own type from the photographs.

Sunscreens and other skin treatment

There is more and more
evidence that both forms of UV damage the skin, but most sunscreens
protect only against UV-B. Some "broad-spectrum" sunscreens protect
against UV-A (ref
11) but it is important to check the UV-A SPF.
Sunscreens do prevent sunburn in fairskinned people, but they may not

provide protection against UV effects on the immune system
(but see Ref 11)

Clothing is a noncontroversial, completely safe way to protect against
sun damage. Loose long clothing like salwar kameez is ideal for
protection, as are long pants and shirts. Cotton clothing has a UPF
(equivalent to SPF) of about 5, and interestingly, well-washed cotton
is even better (Ref
12, so pull out those old kurtas). Sunscreen is necessary only
for the exposed parts of the body.

Whatever your skin colour, sunscreen may be a good idea if you're
planning extended intense sun exposure, such as a day at the beach.

Note that prolonged use of bleaching creams (Fair and Lovely, for
example) can burn the skin because they remove the inherent melanin
protection of brown skin. Most bleaching creams contain hydroquinone
which blocks the production of melanin and also destroys the skin's
melanocytes, thus increasing skin sensitivity to sun. (Ref 8)

Sunscreen and children: Children tend to play and stay in the
sun more than adults. Research indicates that one blistering sunburn
in childhood doubles the risk of skin cancer in later years. (Ref
13), and several web pages assert that most people receive
80% of their lifetime sun exposure by age 18. (e.g. Ref 10), so that
it is very important to protect children from the sun. As with adults,
dark-skinned children have more inherent protection against sun
damage.

Previous recommendations were that sunscreen should not be used on
children under 6 months of age. The American Assoc. of Pediatrics now
says that "when adequate clothing and shade are not available, parents
can apply a minimal amount of sunscren to small areas, such as the
infant's face and back of hands".

Sunglasses

As opposed to skin cancer, cataracts are more common in tropical or
sunny areas. Brown/black eyes don't seem to protect against eye
damage from the sun, unfortunately. A pair of UV-absorbing glasses
are highly recommended.

Prickly Heat

Prickly heat is common in South Asia, and it is not the same as sunburn.
Its official name is milaria,
and it occurs mostly in hot humid environments. The sweat glands get
blocked, sweat is trapped under the skin causing itching. It occurs
under clothing, and even when out of the sun. The cure is to cool and
dry the affected areas.